Cut 200g mushrooms into thin slices, or bite-sized strips. Dice 1 large yellow onion and thinly slice 2 garlic cloves. Heat a large, thick-bottomed pan on medium heat.
Once warm, add 2 tbsp butter and 1 tbsp olive oil. When the butter starts to foam, add mushrooms and stir until evenly coated in butter. Cook until all the mushrooms release their water and start to brown, about 5 minutes. Season with a generous pinch of salt and 1/2 tbsp white wine vinegar. Cook, sturring occasionally, until the vinegar smell evaporates and you’re left with meaty, caramelized mushrooms, about 5-10 minutes.
Add 2 tbsp butter and 1 tbsp oil to the pan along with diced onion and garlic. Cook until completely soft and slightly browned, about 5 minutes. Reduce heat to medium-low and add 1 cup orzo and lots of cracked black pepper. Cook, stirring frequently, until the orzo and pepper are slightly toasted, about 2 minutes.
When you start to smell a nutty aroma from the toasted orzo and pepper, add 3 cups broth and bring to a simmer. Cook for 8-10 minutes, stirring occasionally to avoid sticking.
When the orzo is al dente, and most of the liquid has been absorbed, turn off the heat and add remaining 2 tbsp butter, 3/4 cup parmesan and 1/2 tbsp soy sauce. Stir until the sauce is creamy and glossy. Taste and adjust seasoning. You might want to add another pinch of salt or some more black pepper.
Serve with a drizzle of olive oil and more grated parmesan.
